Fermentation process

摘要

The present invention provides a process for periplasmic expression of a bacterial toxoid comprising the steps of: a) growing a culture of a gram negative host cell in a fermentation medium, wherein the host cell is transformed with a polynucleotide, and wherein the polynucleotide encodes the bacterial toxoid and a periplasmic signal sequence; or providing a gram negative host cell wherein the host cell is transformed with a polynucleotide, the polynucleotide encodes the bacterial toxoid and a periplasmic signal sequence and wherein the gram negative host cell comprises the bacterial toxoid expressed in the periplasm; a(i)) inducing expression of the bacterial toxoid; b) maturing the host cell, wherein the maturing step comprises: I) subjecting the host cell to a pH shock; II) incubating the host cell with no feed addition; and/or III) subjecting the host cell to a temperature below -20°C; and c) extracting the bacterial toxoid from the host cell wherein the extraction process comprises osmotic shock.